Process for breaking petroleum emulsions



Patented July 1, 1952 PRUCESS FOR BREAKING PETROLEUM EMULSIONS Melvin DeGIOOtByUIliVBlSitY City, Mo., assignor to Petrolite Corporation, Ltd,Wilmington, Del, 7 a corporation of Delaware No Drawing. ApplicationSeptember 25, 1950,

" Serial No. 186,685

6 Claims. (Cl. 252-335) My invention provides an economical and rapidprocess for resolving petroleum emulsions of the water-in-oil type thatare commonly referred to as cut oil, roily oil, emulsified oil, etc.,and which comprise fine droplets of naturally-occurring waters or brinesdispersed in a more or less permanent state throughout the oil whichcon- Demulsification as contemplated in the present application includesthe preventive step of commingling the demulsifier with the aqueouscomponent which would or might subsequently become either phase of theemulsion in the absence of such precautionary measure. Similarly, suchdemulsifier may be mixed with the hydrocarbon component.

The demulsifying agent employed in the present process i a mixed estersalt of a 'monobasic acid and a polybasic acid. Three moles of theformer and, more specifically, monocarboxy acids are employed whereasone mole of the latter is employed. The latter is a type in which threecarboxyl radicals appear and one sulfo radical. The carboxyl radicalsappear in ester form and the sulfo radical in salt form. Such compoundsare derived preferably by reaction between four types of reagents: (a)Polypropylene glycol of a molecular weight sufiicient to givewater-insolubility and kerosene-solubility, generally being in themolecular weight range of 750 to approximately the fractional esterobtained from polypropylene glycol and one mole of aconitic acid; andre- Controlled emulsification and subor potassium bisulfite.

. tional equivalents of sodium bisulfite.

alkali metal bisulfite such as sodium bisulfite.

Alternately one can esterify the glycol first with the aconitic acid andthen esterifywith a monocarboxy acid, such as acetic acid. There is nochoice between the two procedures.

More specifically then the present invention is concerned with a processfor breaking petroleum emulsions of the water-in-oil type characterizedby subjecting the emulsion to the action of a demulsifier includinghydrophile synthetic products; said 'hydrophile synthetic products beingcharacterized by the following formula:

0 EKOOaHoMOOCR NaSOa o ocanonoocs' in which 3 is the trivalent radicalof aconitic acid and n a whole number varying from 10 to and R'COZ istheacyl radical of a low molal monocarboxy acid having less than 8carbon atoms, and with the proviso that the polypropylene glycol priorto esterification be water-insoluble and kerosenesoluble. r I g In theabove formula the alkali metal cation is shown as sodium which is thecheapest and most readily available. Needless to say, any other a1- kalimetal cation, such. as potassium, may be employed in the form ofpotassium bisulfite and is included in the hereto attached claims as theobvious chemical equivalent. Similarly, ammonium bisulfite may beemployed instead of sodium This applies also to a bisulfite of variousorganic bases provided, of course, that such cases prior to forming asulfite are as basic as ammonia and that the sulfite is water-soluble.All these are the obvious tune The procedure is illustrated by thefollowing example:

EXAMPLE 1 In a reaction flask there were placed 9.6 grams of glacialacetic acid, and 325 grams of propylene glycol 2025 (molal ratio ofglycol to acid 1:1)

along with one-half of one per cent of toluene culfonic acid. In thisinstance 1.6 grams were used. There were also added 50 c. c. of xylene.Heat was applied and the mixture allowed to reflux for about 3 /2 hours.The maximum temperbe conducted at a suitable temperature until thesodium bisulfite has combined. Thereafter the xylene can be distilledover in the usual manner, removing any water with it and all the xylenecan be removed by distillation, particularly 5 ature during the refluxperiod was 15 .5. C.v At the. vacuum distillation. end of this time lessthan.3 c. c..of water wascar- The same procedure was followed inconnecried over to the phase-separating trap. Simition with a number ofadditional samples, all larly, at the end of this period there was stilla of which are illustrated in the following tables slight acidity due tothe catalyst and also due which give the reactants, amounts employed,perhaps to a small amount of unccmbinedv acetic temperature ofesterfication, etc.

Table 1 M.W.of Max. Ester- Esterifl- I13x. Polyprogggg' 1((ylene i iication ci ation 0. DY 611B com. emp. lme

l l 1) Add (EYSJ 00 2,025 9.6 59 145 3 725 9.5 50 13s 3% 1,025 9.6 50145 3 2,525 9.5 50 145 4 1, 525 9. 5 50, 144 3% 2, 025 12. a 50 145 4125, 12.5 1 50 13s 5 1, 025 12.3 50 140. 3% 2, 525 12; s 50 145' 3% 1,525 12. 3 1 50 13s 4% Amt. M Esterificasminum l e e 9 EL'NOJ. AcidReactant' Used, tion Time tion P (gm Temp (hrs) fite Tem Time (O.)(grs.) (00') .(hrs) 1 AconiticAcid 9.3 145 4- 5 80-95 3. 2-- 1 do 9.3140 3% 5 80,-95 4% a 9.5 145 3% 6 80-95 3% 9.3 140 3% 5- 80-95 3 9.3 1354 5 80-95, 3% 9.3= 141 4 a 80-95 4% 9.3 137 3% 5 80-95 4 9-3 139 4 550-95 3% 9. a 1 140 3% 5' s0-95 4 9.3. 13.7- 4 5 80-95 4% acid. Anadditional one-ha1f per cent of toluene sulfonic acid was added, alongwith 9.3 grams of aconitic acid. Heat was applied and the mixturerefluxed for four hours. The maximum temperature during the secondreflux period, as in the first, was 145 C. The amount of water whichdistilled over in this instance was about the same as in the previousperiod. At the end of the reaction period there was still a slightacidity due to the presence of the acid catalyst and possiblysomeunoombinedaconitic acid, and possibly some uncombined acetic acid.A'small amount of aqueous caustic soda was added until sufficient hadbeen introduced to neutralize the free sulfonic acid radicals and thefree-carboxy-l acid radicals.

After this adjustment -6- grams of powdered sodium bisulfitewere added.Apparently enough water had been added along with the caustic soda todissolve at least part of the sodiumbisulfite so that further additionofwater was not re quired. Needless to say, if no caustic soda solutionwas added to neutralize the acidity then a little water should be addedto dissolve at least part or all of the sodium bisulfite so as to givePolypropylene glycols. are commercially available. Such polypropyleneglycols are furnished in various molecularv weightranges. Thewaterinsoluble, kerosene-soluble polypropylene glycols begin in themolecular weight range somewhere above 500, and more specifically, atabout 700 or 750. The. molecular weight was. usually determined by thehydroxyl method. Such hydroxyl molecular weight is a fractionsometimes alarge major fraction, of the theoretical mole cular weight based on themethod of synthesis, i. e., the calculated molecular weight, basedtheoretically on the value one would expect to obtain by treating wateror propylene glycol, for example, with propylene oxide. Needless to,say. one does not obtain a single compound but a propylene glycol of amolecular weight of 75.0 or 1,000 or 2,000 as the case may be and whichreally represents a cogeneric mixture whose statistical averagemolecular weight is the one indicated. Reference in the table is, ofcourse, to hydroxyl value molecular weight for the obvious reason thatthis is the basis for calculatin the amount of reactants required.

In all instances a small amount of 30% caustic soda was used as in themore complete description of Example 1. Also a small amount oftoluenesulfonic acid, approximately 1 of theweightof the glycol or slightlyless, was used in the two esteriflcation steps. About one-half of thisamount was used inthe first esterification; step (with the monocarboxyacid), and an equal amount. added during the secondesterification step(with the aconitic acid). A larger amount should not be used at any timebecause there may be dGCOmpOSitlOIl of the glycol. The total amount canbe added during the initial esterification if desired. Smaller amountscan be used, for instance, a total of of 1% or /4 of 1% based on theamount of glycol, provided, however, that the esterification time isextended somewhat.

One may use any one of a variety of monocarboxy acids, such as thosepreviously noted, or higher acids of the aliphatic series, such asbutyr-- ic or valeric. The acids may be cyclic as in the case ofbenzoic, cyclohexanoic and furoic. The acid may have the carbon chaininterrupted by an oxygen atom as in the instance of beta-methoxypropionic acid. The acids may be hydroxylated as in the case ofhydroxyacetic acid or lactic acid. In any event, however, the acids mustbe free from any radical having 8 or more uninterrupted carbon atoms ina single group.

One need not prepare the ester in the manner described above but may usesome other conventional procedures, as, for example, the use of the acylchloride instead of the acid, or by alcoholysis involving methyl orethyl acetate, ethyl or methyl propionate, etc. One may also start withthe acid itself, such as acetic acid or propionic acid and subject suchacid to oxypropylation until the desired molecular Weight is reached.

The products obtained are comparable to the initial glycol inappearance, etc., i. e., usually they are an amber color or at least ofa slight straw color, and often somewhat thicker than the originalglycol. This description, of course, applies to materials after removalof the solvent, 1. e., the Xylene. For use as demulsifiers there is noneed to remove the xylene and it may remain behind. Obviously otherliquids than xylene may be used in esterification procedure. However, ifthe boiling point is any higher than xylene there is danger thatdecomposition may take place unless the amount of sulfonic acid isreduced. Other catalysts such as a small amount of dry hydrochloric acidcan be used but it appears less desirable than the sulfonic acid.Needless to say the caustic soda solution used neutrali es the sulfonicacid catalyst present.

In the various examples preceding only one glycol has been used in thesecases. Actually there is no reason Why one may not use two differentglycols, for instance, an equimolar mixture of two glycols, one forexample, having a molecular weight of 2000 and the other 3000; or onehaving a molecular weight of 1500 and the other 2500. Actually theseglycols are cogeneric mixtures at each selected molecular Weight. Sinceaconitic acid has three carbcxyls one could select glycols of threediiierent molecular weights, for instance, 1500, 2250 and 3000.Momentarily one need only look at a simple situation, i. e., if maleicacid were employed, i. e., a compound having two carboxyl radicalsinstead of three. In such event if one does make a mixture of the kindhere described actually three types of compounds will appear, one typein which both carboxyl radicals of the dicarboxy acid are joined withthe higher glycol, one type where both carboxyl are joined with thelower molecular weight glycol, and one type Where one carboxyl is unitedto a higher molecular weight glycol and the other one to a lowermolecular weight glycol.

Other variations are obviously possible by using difierent monocarboxyacids. For example, the aconitic acid can be used united with differentesters of the same glycol, for instance, acetic acid 6, ester andpropionic acid ester, or the different acids might be joined to glycolsof diilerent molecular weights.

The products so obtained are peculiar (a) insofar that there is notpresent any radical having 8 or more uninterrupted carbon atoms, and (b)the compounds are not particularly effective as surface-active agents inthe ordinary sense due either to the large molecular size or the absenceof a hydrophobe radical of the kind previously referred to, or for someother reason which is obscure. The chemical compounds herein employed asdemulsifiers have molecular weights varying from 1500 up to severalthousands, for instance, 6000, 7500 and 9000, and yet contain only onesulfo radical. Utility of such compounds for industrial uses is ratherunusual. They are not efiective emulsifying agents, but are valuable asan additive or a promoter of emulsions. These compounds also havehydrotropic property and serve as common solvents in the preparation ofmicellar solutions. It is to be noted that they are free from terminalcarboxyl radicals and thus differ from reagents obtained, for example,by treating one mole of a high molal polypropylene glycol with 2 molesof a dicanboxy acid. It is probable these reagents, due to theirpeculiar structure and their peculiar solubility characteristics, willfind utility in other fields of application now unknown.

Conventional demulsifying agents employed in the treatment of oil fieldemulsions are used as such, or after dilution with any suitable solvent,such as water, petroleum hydrocarbons, such as benzene, toluene, xylene,tar acid oil, cresol, anthracene oil, etc. Alcohols, particularlyaliphatic alcohols, such as methyl alcohol, ethyl alcohol, denaturedalcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol,etc., may be employed as diluents. Miscellaneous solvents such as pineoil, carbon tetrachloride, sulfur dioxide extract obtained in therefining of petroleum, etc., may be employed as diluents. Similarly, thematerial or materials employed as the demulsifying agent of our processmay be admixed with one or more of the solvents customarily used inconnection with convential demulsifying agents. Moreover, said materialor materials may be used alone or in admixture with other suitablewellknown classes of demulsifying agents.

It is Well known that conventional demulsifying agents may be used in awater-soluble form, or. in an oil-soluble form, or in a form exhibitingboth 011- and water-solubility. Sometimes they may be used in a formwhich exhibits relatively limited oil-solubility. However, since suchre-' agents are frequently used in a ratio of l to 10,000 or 1 to20,000, or 1 to 30,000, or even 1 to 40,000, or 1 to 50,000-as indesalting practice, such an apparent insolubility in oil and water isnot Significant because said reagents undoubtedly have solubility withinsuch concentrations. This same fact is true in regard to the material ormaterials employed as the demulsifying agent of our process.

In practicing our process for resolving petroleum emulsions of thewater-in-oil type, a treating agent or demulsifying agent of the kindabove described is brought into contact With or caused to act upon theemulsion to be treated, in any of the various apparatus now generallyused to resolve or break petroleum emulsions with a chemical reagent,the above procedure being used alone or in combination with otherdemulsifying procedure, such as the electrical dehydration process.

One type of procedure is to accumulate a volume of emulsified oil in atank and conduct a batch treatment type of demulsification. procedure torecover clean oil. In this procedure the emulsion is admixed with thedemulsifier, for example by agitating the tank of emulsion and slowlydripping demulsifier into the, emulsion. In some cases mixing isachieved by heating the emulsion while dripping in the demulsifier,depending upon the convection currents in the emulsion to producesatisfactory admixture. In a third modificationoi this type oftreatment, a circulating pump withdraws emulsion from, e. g., the bottomof the tank, andre-introduces it into the,v top of the; tank, thedemulsifler being added, forexample, at thesuctionside of .saidcirculating pump.

In a second type of. treating procedure, the demulsifler is introducedinto the well fluids at the well-head or at some point between thewell-head and the final oil storage tank, by means of an adjustableproportioning mechanism or proportioning pump. Ordinarily the flow offluids through the subsequent lines and fittings suffices toproduce thedesired degree of mixing of demulsifier and emulsion, although in someinstances additional mixing devices may be introduced into the flowsystem. In this general procedure, the system may include variousmechanical devices for Withdrawing free water, separating entrainedwater, or accomplishing quiescent settling of the chemicalized emulsion.Heating devices may likewise be incorporated in any of the treatingprocedures described herein.

A third type of application (doWn-the-hole) of demulsifier to emulsionis to introduce the'demulsifier either periodically or continuously indiluted or undiluted form into the well and to allow it to come to thesurface with the well fluids, and then to flow the chemicalized emulsionthrough any desirable surface equipment, such as employed in the othertreating procedures. This particular type of application is decidedlyuseful when the demulsifier is used in connection with acidification ofcalcareous oil-bearing strata, especially if suspended in or dissolvedin the acid employed for acidification.

In all cases, it will be apparent from the foregoing description, thebroad process consists simply in introducing a relatively smallproportion of demulsifier into a relatively large proportion ofemulsion, admixing the chemical and emulsion, either through naturalflow or through special .apparatus, with or without the application ofheat, and allowing the mixture to stand quiescent until the undesirableWater content of the emulsion separates and settles from the mass.

The following is a typical installation:

A reservoir to hold the demulsifler of the kind described (diluted orundiluted) is placed at the well-head where the efiluent liquids leavethe well. This reservoir or container, which may vary from gallons to.50gallons for convenience, is connected to a proportioning pump whichinjects the demulsifler drop-wise into the fluids leaving the well. Suchchemicalized fluids pass through the flowline into a settling tank. Thesettling tank consists of a tank of any convenient size, for instance,one which will hold amounts of fluid produced in 4 to 24 hours (500barrels to 2000 barrels capacity), and in which there is a perpendicularconduit from the top of the tank to almost the very bottom, so as topermit the incoming fluids to pass from thetop of. the settling tank tothe bottom, so that such incoming fluids do not disturb Stratificationwhich takes place during the course of demulsification. The. settlingtank has two outlets, one being below the water level to drain off thewater resulting from demulsification or accompanying the emulsion asfree water, the other being an oil outlet at the top to permit thepassage of dehydrated oil to a second tank, being a storage tank, whichholds pipeline or dehydrated oil. If desired, the conduit or pipe whichserves to carry the fluids from the well to the settling tank mayinclude a section of pipe with balfles to serve as a mixer, to insurethorough distribution of the demulsifier throughout the fluids, or aheater for raising the temperature of the fluids to some convenienttemperature, for instance, to or both heater and mixer.

Demulsification procedure is started by simply setting the pump so as tofeed a comparatively large ratio of demulsifier, for instance, 115,000.As soon as a complete break or satisfactory demulsiflcation is obtained,the pump is regulated until experience shows that the amount ofdemulsifier being added is just suflicient to produce clean ordehydrated oil. The amount being fed at such stage is usually 1110,000,1:15,,000, 1:20,000, or the like.

In many instances the products. herein specified as demulsifiers can beconveniently used without dilution. However, as previously noted, theymay be diluted as desired with any suitable solvent. For instance, bymixing 75 parts by weight of such derivative, for example, the productof Example 1, with 15 parts by weight of xylene and 10 parts by weightof isopropyl alcohol, an excellent demulsifier is obtained. Selection ofthe solvent will vary, depending uponthe solubility characteristics ofthe product, and of course will be dictated in part by economicconsiderations, i. e., cost.

As noted above, the products herein described may be used not only indiluted form, but also may be admixed with some other chemicaldemulsifler. A mixture which illustrates such combination is thefollowing:

The product of Example 1, 20%;

A cyclohexylamine salt of a polypropylated naphthalene monosulfonicacid, 24%;

An ammonium salt of a polypropylated naphthalene monosulionic acid, 24%;

A sodium salt of oil-soluble mahogany petro leum sulfonic acid, 12%;

A high-boiling aromatic petroleum solvent,

Isopropyl alcohol, 5%.

The above proportions are all weight percents.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is

l. A process for breaking petroleum emulsions of the water-in-oil typecharacterized by subjecting the emulsion to the action of a demulsifierincluding hydrophile synthetic products; said hydrophile syntheticproducts being characterized by the following formula:

aHo)nOOCR NaSOa 0 ooinonooon' in which is the trivalent radical ofaconitic acid and n is a whole number varying from 10 to 80 and R'CO isthe acyl radical of a low molal monocarboxy acid having less than 8carbon atoms, and with the proviso that the corresponding polypropyleneglycol of the formula HO(C3H60)nH be waterinsoluble andkerosene-soluble.

2. The process of claim 1 wherein the value of n is approximately 15.

3. The process of claim 1 wherein the value of n is approximately 25.

4. The process of claim 1 wherein the value of n is approximately 35.

5. The process of claim 1 wherein the value of n is approximately 45.

6. The process of claim 1 wherein the value of n is approximately 55.

MELVIN DE GROO'I'E.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

1. A PROCESS FOR BREAKING PETROLEUM EMULSIONS OF THE WATER-IN-OIL TYPECHARACTERIZED BY SUBJECTING THE EMULSION TO THE ACTION OF A DEMULSIFIERINCLUDING HYDROPHILE SYNTHETIC PRODUCTS; SAID HYDROPHILE SYNTHETICPRODUCTS BEING CHARACTERIZED BY THE FOLLOWING FORMULA: